Fix issue Connect-AzAccount fail in multi-threaded execution

src/Accounts/Accounts/ChangeLog.md

@@ -18,6 +18,7 @@
         - Additional information about change #1
 -->
 ## Upcoming Release
+* Fixed an issue that may cause `Connect-AzAccount` to fail in multi-threaded execution [#11201]
 
 ## Version 1.8.1
 * Fixed an issue that may cause Az to skip logs in Azure Automation or PowerShell jobs [#11492]

src/Accounts/Authentication/AzureSessionInitializer.cs

@@ -254,18 +254,24 @@ public override SourceLevels AuthenticationTraceSourceLevel
             /// <summary>
             /// Adal Logger for Adal 3.x +
             /// </summary>
-            public AdalLogger AdalLogger { get; private set; }  
+            public AdalLogger AdalLogger { get; private set; }
 
             /// <summary>
             /// Write messages to the existing trace listeners when log messages occur
             /// </summary>
             /// <param name="message"></param>
             private void WriteToTraceListeners(string message)
             {
-                foreach (var listener in AuthenticationTraceListeners)
+                for (var i = 0; i < AuthenticationTraceListeners.Count; ++i) // don't use foreach, enumerator is not thread safe
                 {
-                    var trace = listener as TraceListener;
-                    trace.WriteLine(message);
+                    try
+                    {
+                        AuthenticationTraceListeners[i].WriteLine(message);
+                    }
+                    catch
+                    {
+                        // ignroe any exception
+                    }
                 }
             }
 #endif